Vaporizers contain various forms of extraction chambers including straight bore, venturi, or sequential venturi, and are made of materials such as metal or glass. The extracted vapor may be collected in an inflatable bag, or inhaled directly through a hose or pipe. When used properly, cooler temperatures due to lack of combustion[1] result in significantly more efficient extraction of the ingredients. Hence, the irritating and harmful effects of smoking are heavily reduced,[2][3][4][5][6] as is its secondhand smoke.

Dry herb vaporizers can be used to inhale marijuana.[29] Of the studies about vaporizing marijuana, few have addressed the quality of the vapor extracted and delivered; instead, studies usually focus on the mode of usage of the vaporizers. There are 483 identifiable chemical constituents known to exist in the cannabis plant,[30] and at least 85 different cannabinoids have been isolated from the plant.[31] The aromatic terpenoids begin to vaporize at 126.0 °C (258.8 °F),[32] but the more bio-active tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) do not vaporize until near their respective boiling points: THC 157 °C (315 °F),[33] CBD 160–180 °C (320–356 °F),[33] and CBN 185 °C (365 °F).[33]

Vaporizers can also be used to inhale cannabis oil and waxy concentrates that have been extracted from the plant. Sometimes the oil is also mixed with propylene glycol and polyethylene glycol to make it less viscous.[34]

Vaporizing is more efficient than smoking, because approximately 30% of THC in marijuana or hashish cigarettes is destroyed by pyrolysis during smoking.[35]

Vaporizer with water cooling

A conduction-style vaporizer

A passive-convection “vaporization pipe” with flame filter

A portable radiation vaporiser

A Storz & Bickel Volcano, a forced-air vaporizer. The detachable balloon (top) fills with vapors that are then inhaled

Vaporizers can be used to inhale other recreational drugs as well. A wide variety can be consumed this way, either dissolved in e-liquid or vaporized directly.[36] The use of e-cigarettes to inhale the psychedelic drugDMT has been reported.[37]

Studies have shown that vaporizing cannabis exposes the user to lower levels of harmful substances than smoking cannabis.[38][39][40][41] These findings are important for it is estimated that 10–20 percent of patients with chronic pain, multiple sclerosis, epilepsy, and HIV/AIDS have admitted to smoking cannabis for therapeutic purposes. For patients, a study found that smoking cannabis sativa reduced daily pain by 34%, a statistically significant amount.[42]

In a study published in the Journal of Psychopharmacology in May 2008, it was stated that vaporizers were a “suitable method for the administration of THC”.[43] A 2007 study by the University of California, San Francisco, published in the Journal of the American Academy of Neurology, found that “there was virtually no exposure to harmful combustion products using the vaporizing device”.[5] A 2006 study performed by researchers at Leiden University found that vaporizers were “safe and effective cannabinoid delivery system(s)”. The study stated that the amount of THC delivered by vaporizers were equivalent to the amount delivered by smoking.[41] Because of those studies and other studies, vaporizers are considered medically sound devices for delivering THC.[44]

Not all those have been scientifically tested. Research using vaporizers found the delivery efficiency highest at around 226 °C (439 °F), falling to about half efficiency at 150 °C (302 °F) to 180 °C (356 °F) degrees depending on material.[41] The purest preparations produced the highest efficiencies, about 56% for pure THC versus 29% for plant material (female flower tops) with 12% THCA content. Besides THC, several other cannabinoids as well as a range of other plant components including terpenoids were detected in the plant material. Using pure THC in the vaporizer, no degradation products (delta-8-THC (D8-THC), cannabinol (CBN), or unknown compounds) were detected by HPLC analysis.[41] The longer vapor is stored, the more THC is lost as it condenses on the surface of the vaporizer or the balloon. This loss may be negligible over a few minutes but may exceed 50% after 90 minutes.[41] The Leiden University study found that as much as 30–40% of inhaled THC was not absorbed by the lungs but simply exhaled. However, they did not find large individual differences in the amounts exhaled.[41]

Vaporizers are sometimes used by chefs as a method of applying controlled heat to herbs and spices to release flavors that are otherwise difficult to titrate or apply, or that might be spoiled by overheating during cooking.[45][46][47] Grant Achatz, chef-proprietor of Alinea in Chicago, “uses the aroma-filled bags as place-mats, punctured when plates are placed in front of the customer”.[45]